N54 E89 35i vs 35is using MHD

pbondar

Lurker
May 30, 2020
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So I have an E89 Z4 35is with a N54 engine..

On the 35is the DME software has an overboost facility plus an additional increase in BHP / torque over the N54 in the 35i..

Question:

If I use MHD to flash one of their stock re-maps how does that effect the overboost and/or the differntial BHP/torque of a 35is vs 35i

ie If you are reflashing a N54 do you 'lose' the 35is advantages?
 

General.Massacre

Corporal
May 14, 2018
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2009 E92 335i DCT
Good question, Im very interested to see the answer on this.
To my knowledge, i believe the OTS maps overwrite that and handle the base requirements, but this also goes off whatever the VIN states is available for the car.

I know that on my car, i have a 335i DCT, and i had a Z4 35is map adjusted to work on my car to work around the LPFP requirements and Steering difference to Hydraulic,
the base worked like a charm, but when i flashed the OTS map for Stg2+, then MHD overwrote the changes and i had the CEL for the Fuel PUMP immediately.

But i look forward to this thread info.
 

pbondar

Lurker
May 30, 2020
17
5
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Good question, Im very interested to see the answer on this.
To my knowledge, i believe the OTS maps overwrite that and handle the base requirements, but this also goes off whatever the VIN states is available for the car.

I know that on my car, i have a 335i DCT, and i had a Z4 35is map adjusted to work on my car to work around the LPFP requirements and Steering difference to Hydraulic,
the base worked like a charm, but when i flashed the OTS map for Stg2+, then MHD overwrote the changes and i had the CEL for the Fuel PUMP immediately.

But i look forward to this thread info.
Hi..not sure what conditional logic the 35is uses to branch to / add the extra boost when overtaking..there are a number of prerequsites before it allows the event to happen..

I'm going to do a baseline dyno run after some fresh plugs n coils and a de-coke of the inlets and then do a first MHD flash before I do any other modding to see where its at..then come back to the same dyno once the Wagner EVO FMIC is fitted and VSRF decat downpipes and a few inelt side pipe changes..
 

General.Massacre

Corporal
May 14, 2018
200
43
0
Ride
2009 E92 335i DCT
Hi..not sure what conditional logic the 35is uses to branch to / add the extra boost when overtaking..there are a number of prerequsites before it allows the event to happen..

I'm going to do a baseline dyno run after some fresh plugs n coils and a de-coke of the inlets and then do a first MHD flash before I do any other modding to see where its at..then come back to the same dyno once the Wagner EVO FMIC is fitted and VSRF decat downpipes and a few inelt side pipe changes..
I would recommend a Custom tune in this retrospect, as you just building on the current base map, the OTS maps are good, but they do have their limits. ive seen this first hand from my friends Z4 35i (not "is"),
 

pbondar

Lurker
May 30, 2020
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I would recommend a Custom tune in this retrospect, as you just building on the current base map, the OTS maps are good, but they do have their limits. ive seen this first hand from my friends Z4 35i (not "is"),
Hello…your advice is noted…having tweaked heavily my N20 E89 I needed to use a custom tuner..

Im trying, st this stage, to see what I can do ‘from home’ with MHD..

I guess if I could find a local N54 tuning guru I may change my mind..

I have lots of chassis/ audio/cosmetic work to do so I’ll see how I get on MHD at this stage..

At least I can revert back to ‘stock’ on my own..

Again thnx for your advice..
 

General.Massacre

Corporal
May 14, 2018
200
43
0
Ride
2009 E92 335i DCT
Hello…your advice is noted…having tweaked heavily my N20 E89 I needed to use a custom tuner..

Im trying, st this stage, to see what I can do ‘from home’ with MHD..

I guess if I could find a local N54 tuning guru I may change my mind..

I have lots of chassis/ audio/cosmetic work to do so I’ll see how I get on MHD at this stage..

At least I can revert back to ‘stock’ on my own..

Again thnx for your advice..
Pleasure mate.

Where in the world you from if you dont mind me asking? Im from South Africa, and my mate and i have had good success with our tuner, i know there are a host of them to choose from.
and we are at elevation of about 5700ft.
 

pbondar

Lurker
May 30, 2020
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Pleasure mate.

Where in the world you from if you dont mind me asking? Im from South Africa, and my mate and i have had good success with our tuner, i know there are a host of them to choose from.
and we are at elevation of about 5700ft.
Hello..I’m in the UK..in Southern Scotland..there are quite a few tuners but separating the ‘wheat from the chaff’ is the issue…

The N20 I was tweaking has very little UK support..part of the reason for the swap is N54 support is much more extensive 👍
 

carabuser

Sergeant
Oct 2, 2019
342
222
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UK
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Z4 35i & 335i
The 35is overboost functionality will go when you flash an MHD map.

The overboost function was just a temporary adder to the load target which was time limited, you wouldn't want to keep it. The logic is present in the 35i too but the adder is set to 0.

Be careful when it comes to upgrade shopping on the Z4. The charge pipe upgrade isn't needed on the Z4, the standard one is not a failure point like the 335i. Also the intake system is improved over other N54 cars so installing dual cone intakes will be a step backward.
 

pbondar

Lurker
May 30, 2020
17
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The 35is overboost functionality will go when you flash an MHD map.

The overboost function was just a temporary adder to the load target which was time limited, you wouldn't want to keep it. The logic is present in the 35i too but the adder is set to 0.

Be careful when it comes to upgrade shopping on the Z4. The charge pipe upgrade isn't needed on the Z4, the standard one is not a failure point like the 335i. Also the intake system is improved over other N54 cars so installing dual cone intakes will be a step backward.
Thank you for your advice…to take your points further..

So a MHD flash of a 35i will yield the same result as a 35is?

So you say the charge pipe and air inlet are more than adequate for a MHD level tune…what evidence / experience / support is that based on pls ?

Finally apart from a VSRF down pipe what other mods would you recommend?

uprated dv

air box to turbo pipes

uprated boost pressure control valve

I assume a FMIC is still a good idea..I’ve got a Wagner Evo 1 already from a previous project
 

carabuser

Sergeant
Oct 2, 2019
342
222
0
UK
Ride
Z4 35i & 335i
Thank you for your advice…to take your points further..

So a MHD flash of a 35i will yield the same result as a 35is?

So you say the charge pipe and air inlet are more than adequate for a MHD level tune…what evidence / experience / support is that based on pls ?

Finally apart from a VSRF down pipe what other mods would you recommend?

uprated dv

air box to turbo pipes

uprated boost pressure control valve

I assume a FMIC is still a good idea..I’ve got a Wagner Evo 1 already from a previous project

Yes, it's the same engine and hardware. Overboost is just a marketing term.
BMW allowed a temporary uplift on boost pressure in the 35is to achieve higher peak engine output but didn't upgrade the intercooler so to avoid over stressing the small standard intercooler they limited the increased boost pressure to short bursts so after you've had your temporary power boost the engine will revert to 35i boost levels.

With a tune you just ignore the overboost logic and target as much boost as you want (and your fuel/mods can support) without it becoming unavailable after a few seconds.

As far as proof that chargepipe, diverter valves and dual cone (hot air) intakes are useful. I'd be asking the inverse question, what makes you think you need to change your chargepipe or that diverter valves are a problem? Stories of shattering chargepipes come from 335i users which have different pipework.

I've had my 35i for 9 years now. I've driven 80,000 miles in it, most of which are tuned. It's still on stock turbos but I'm running 20PSI peak boost tapering down to 16PSI at the top end. My stock chargepipe is still intact. My stock diverter valves seem fine as my WGDC is exactly where it should be for the boost.

Dual cone intakes are contentious on the 335i, I've seen no good data showing that they are beneficial but plenty to suggest that they provide inadequate filtering. I'm more concerned about getting clean cold air into the engine than worrying about 1 or 2 best-case scenario horsepower. On the Z4 it has been well documented that the air intake box flows better so I don't see any merit for changing that.

The problem with car forums in general, and why I like spoolstreet more than the other BMW forums, is that most of them are run by greed. You have a load of vendors selling tat that will jump in on any new user (just look at any E90post thread) and tell them that they need a billet oil filter cap and some huge ricer air filters. In general you want to avoid any tat from the likes of BMS, they are the kings of pointless engine bay bling.

If you want to make more power with your 35is then you just need MHD, some downpipes and a good intercooler. That will have you at a nice easy 400hp. If you want more then a custom tune might get you another 20hp. After that you'll need bigger turbos as the UK has no E85.
 

pbondar

Lurker
May 30, 2020
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Thanks for the detailed reply….don’t take my comments as a negative slur on you but you can forgive me, as you say, there are many ‘shoot from the hip’ experts so trying to baseline people’s comments..

I agree the K+N type filters don’t have a good reputation for filtration..

On the E89 N20, the air intake (which looks very similar to the 35i intake) seemded more than adequate but the 35i when tuned is sucking another w5%-33% more air..

Well I think I’ll save myself a few pennies if I follow your advice..

my main line of thinking was if I was paying someone to take parts apart to fit upgrades that was the time to do any ‘enhancements’

A final question ..assuming a MHD flash tune with down pipes do you advocate one stage cooler plugs?
 

carabuser

Sergeant
Oct 2, 2019
342
222
0
UK
Ride
Z4 35i & 335i
Thanks for the detailed reply….don’t take my comments as a negative slur on you but you can forgive me, as you say, there are many ‘shoot from the hip’ experts so trying to baseline people’s comments..

I agree the K+N type filters don’t have a good reputation for filtration..

On the E89 N20, the air intake (which looks very similar to the 35i intake) seemded more than adequate but the 35i when tuned is sucking another w5%-33% more air..

Well I think I’ll save myself a few pennies if I follow your advice..

my main line of thinking was if I was paying someone to take parts apart to fit upgrades that was the time to do any ‘enhancements’

A final question ..assuming a MHD flash tune with down pipes do you advocate one stage cooler plugs?
Not sure about plugs, you can't go wrong with 1 step colder but it's not essential at these power levels. I have tried NGK 95770 plugs in the past and currently have Bosch ZR5TPP33 (gapped at 0.022"). Both worked fine and are 1 stage colder but my idle is always smoother on stock plugs.

It's hard to directly compare their power potential but I feel that both the 1 step colder plugs have less timing corrections. Next time I change them I might try a different gap setting to see if I can match the smooth idle of stock plugs.

 

pbondar

Lurker
May 30, 2020
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Not sure about plugs, you can't go wrong with 1 step colder but it's not essential at these power levels. I have tried NGK 95770 plugs in the past and currently have Bosch ZR5TPP33 (gapped at 0.022"). Both worked fine and are 1 stage colder but my idle is always smoother on stock plugs.

It's hard to directly compare their power potential but I feel that both the 1 step colder plugs have less timing corrections. Next time I change them I might try a different gap setting to see if I can match the smooth idle of stock plugs.

I’ll put my one stop cooler NGK plugs at standard gap 30 thou? and see what happens 👍